I think Lukaku will make Chelsea more threatening, having good players assisting him, then this tank will be unstoppable imo. Inter's scudetto was won partially thanks to him (among others) but he did quite good job there. I don't see why he will drop in performance with better squad.
Confidence and support from other players is important to see him consistently scoring goals. Football is a team game and Lukaku needs a lot of support from other players to make him dangerous in front of goal. Since Chelsea got it back from Inter, this will make the title race even more fierce in the EPL.